MRI-guided Laser Interstitial Thermal Therapy Research Articles

497 Superficial MRI-guided Laser Interstitial Thermal Therapy (LITT) for Intracranial Metastasis Is Associated With a Significantly Higher Rate of Leptomeningeal Disease

INTRODUCTION: Evolving brain metastases treatment standards has led to shifting intracranial recurrence patterns, especially with respect to pachymeningeal and leptomeningeal disease (PMD/LMD). As an emerging technique, it remains unclear if the depth of magnetic resonance imaging-guided laser interstitial thermal therapy (LITT) is associated with frequency of iatrogenic PMD/LMD. METHODS: A single-institute retrospective analysis of patients who underwent LITT surgery between 2014 and 2022 was conducted to investigate the development of PMD/LMD. P-values <0.05 were considered statistically significant. RESULTS: Eleven patients undergoing thirteen LITT procedures were analyzed. Mean age was 62.6 (±11.7), and 69.2% of patients were female. PMD/LMD developed in 4/13 cases (30.8%). There was no significant difference between superficial vs. deep LITT ablation in terms of age, sex, follow-up time, and primary cancer site. Superficial LITT ablation had a significantly higher frequency of PMD/LMD compared to deep LITT ablation (p = 0.02). Time to PMD/LMD development among patients who underwent superficial LITT ablation was significantly shorter compared to that among patients who had deep LITT ablation (p = 0.02). CONCLUSIONS: Superficial LITT ablation was associated with significantly higher frequency and shorter time to PMD/LMD development compared to deep LITT ablation. These results suggest that iatrogenic PMD/LMD spread during superficial LITT ablation may increase the proportion of PMD/LMD and accelerate disease timeline.

Unilateral Magnetic Resonance Imaging-Guided Laser Interstitial Thermal Therapy Thalamotomy for Essential Tremor.

Essential tremor (ET) affects numerous adults, impacting quality of life (QOL) and often defying pharmacological treatment. Surgical interventions like deep brain stimulation (DBS) and lesional approaches, including radiofrequency, gamma-knife radiosurgery, and magnetic resonance imaging (MRI)-guided focused ultrasound, offer solutions but are not devoid of limitations. This retrospective, single-center, single-blinded pilot study aimed to assess the safety and efficacy of unilateral MRI-guided laser interstitial thermal therapy (MRIg-LITT) thalamotomy for medically intractable ET. Nine patients with ET, unresponsive to medications and unsuitable for DBS, underwent unilateral MRIg-LITT thalamotomy. We assessed tremor severity, QOL, cognitive function, and adverse events (AE) over a 12-month period. Tremor severity significantly improved, with a reduction of 83.37% at 12 months post-procedure. QOL scores improved by 74.60% at 12 months. Reported AEs predominantly included transient dysarthria, proprioceptive disturbances, and gait balance issues, which largely resolved within a month. At 3 months, 2 patients (22%) exhibited contralateral hemiparesis requiring physiotherapy, with 1 patient (11%) exhibiting persistent hemiparesis at 12 months. No significant cognitive impairment was detected post-procedure. Unilateral MRIg-LITT thalamotomy yielded substantial and enduring tremor alleviation and enhanced QOL in patients with ET that is resistant to medication. The AE profile was acceptable. Our findings support the need for additional research with expanded patient cohorts and extended follow-up to corroborate these outcomes and to refine the role of MRIg-LITT as a targeted and minimally invasive approach for ET management. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Preclinical assessment of a noncooled MR thermometry-based neurosurgical laser therapy system.

MRI-guided laser interstitial thermal therapy (MRgLITT) has recently gained interest as an ablative stereotactic procedure for intractable epilepsy, movement disorders, and brain tumors. Conventionally, a LITT system consists of a laser generator and cooled laser applicator, which is a fiber optic core surrounded by a sheath through which cooled fluid is pumped. However, this footprint can make the system bulky and nonmobile, limit the maximum depth of targeting, and increase the chances of breakdown. Herein, the authors conduct a preclinical assessment of a noncooled MRgLITT system in a porcine model. Three-tesla MRI was used to guide the in vivo placement of noncooled laser applicators in the porcine brain. The study consisted of a survival arm and terminal arm. The laser was activated at a power of 4-7 W for ≤ 180 seconds. Temperature changes were monitored using the MR thermometry software ThermoGuide in the survival arm (n = 5) or both ThermoGuide software and adjacently inserted thermal probes in the terminal arm (n = 3). Thermal damage was determined by the software using the temperature-time relationship of cumulative equivalent minutes at 43°C (CEM43). Temperatures calculated by the software were compared with those recorded by the temperature probes. The dimensions of thermal damage thresholds (TDTs; 2-9, 10-59, 60-239, ≥ 240 CEM43 isolines) given by MR thermometry were compared with the dimensions of irreversible damage on histopathological analysis. There was a strong correlation between temperature recordings by ThermoGuide and those by thermal probes at both 4 mm (r = 0.96) and 8 mm (r = 0.80), with a mean absolute error of 0.76°C ± 2.13°C and 0.17°C ± 1.65°C at 4 and 8 mm, respectively. The area of 2-9 CEM43 was larger than the area of irreversible damage seen on histopathological analysis. The dimensions of the 10 and 60 CEM43 correlated well with dimensions of the lesion on histopathological analysis. A well-defined border (≤ 1 mm) was observed between the area of irreversible damage and healthy brain tissue. This preclinical assessment showed that the noncooled LITT system was able to precisely reach the target and create well-defined lesions within a margin of safety, without any adverse effects. MR thermometry software provided an accurate near-real-time temperature of the brain tissue, and dimensions of the lesion as visualized by the software correlated well with histopathological findings. Further studies to test the system's efficacy and safety in human subjects are in progress.

Laser interstitial thermal therapy as a radiation-sparing approach for central nervous system tumors in children with cancer predisposition syndromes: report of a child with Li-Fraumeni syndrome. Illustrative case.

Ionizing radiation and alkylating chemotherapies increase secondary malignancy risk in patients with cancer predisposition syndromes (CPSs), such as Li-Fraumeni syndrome. Laser interstitial thermal therapy (LITT) is a minimally invasive ablation technique that has not been associated with mutagenic risks. We describe the case of a child with LFS and a history of treated choroid plexus carcinoma (CPC) who developed a second primary glial tumor that was safely treated with magnetic resonance imaging (MRI)-guided LITT. A 4-year-old male with left parietal World Health Organization grade III CPC associated with a TP53 germline mutation was evaluated. The patient underwent neoadjuvant platinum-based chemotherapy before near-total resection, followed by 131I-8H9 immunotherapy and 30 fractions of 54-Gy proton radiotherapy. He remained without evidence of disease for 2 years before developing a slow-growing mass adjacent to the left frontal ventricular horn. Stereotactic biopsy revealed a glial neoplasm. Given the nonsuperficial location and focality of the lesion, MRI-guided LITT was performed for ablative therapy. There were no complications, and 2 years of surveillance revealed continued retraction of the ablated tumor focus and no subsequent disease. Alternatives to mutagenic therapies for brain tumors should be explored for patients with CPS. LITT paired with imaging surveillance is a logical strategy to ensure durable outcomes and mitigate treatment-related secondary neoplasms.

Functional outcomes in MRI-guided laser interstitial therapy for temporal lobe epilepsy: a systematic review and meta-analysis.

The use of MRI-guided laser interstitial thermal therapy (MRgLITT) has emerged as a promising treatment option for patients with drug-resistant temporal lobe epilepsy (TLE). Although the minimally invasive approach holds promise as an effective treatment for achieving seizure freedom, a comprehensive review of its impact on functional outcomes is still warranted. To address this need, this review aims to summarize data pertaining to the functional and neurocognitive outcomes following MRgLITT for TLE. Four primary electronic databases were screened following PRISMA guidelines by two independent reviewers. All functional data related to cognitive, behavioral, and emotional outcomes were gathered and analyzed as well as the neuropsychological tests issued to assess pre- and postoperative outcomes. The functional outcomes assessed were grouped into the 5 most common categories: verbal cognition, visual cognition, cognitive emotion, visual deficits, and other higher-order cognitive functioning. A total of 4184 studies were screened and ultimately 408 patients from 14 studies were included for analysis. Changes in functional areas were assessed by comparing pre- and postoperative scores across a comprehensive set of 31 different functional and cognitive assessments, and were tabulated as the percentage of patients whose status improved, declined, or was maintained, where possible. In verbal (n = 112) and visual (n = 42) cognition, the rates of patients experiencing a decline were 20.4% and 13.5%, respectively, and the rates of improvement were 24.9% and 16.7%, respectively. Other functional outcomes assessed, including cognitive emotion (n = 150), visual deficits (n = 325), and higher-order cognitive processes like attention/processing (n = 19), motor cognition (n = 18), and general executive function (n = 4), exhibited varying rates of decline, ranging from 10.5% to 25%. MRgLITT is an effective and minimally invasive surgical alternative treatment for TLE, but there is an observable impact on patient functioning and cognitive status. This review demonstrates the need for standardized methods that can accurately capture and quantify the associated risk of MRgLITT to optimize its effect on patient quality of life moving forward.

Withdrawal of antiseizure medications after MRI-Guided laser interstitial thermal therapy in extra-temporal lobe epilepsy.

This study investigated the success rate of antiseizure medications (ASMs) withdrawal following MRI Guided Laser Interstitial Thermal Therapy (MRg-LITT) for extra-temporal lobe epilepsy (ETLE), and identified predictors of seizure recurrence. We retrospectively assessed 27 patients who underwent MRg-LITT for ETLE. Patients' demographics, disease characteristics, and post-surgical outcomes were evaluated for their potential to predict seizure recurrence associated with ASMs withdrawal. The median period of observation post MRg-LITT was 3 years (range 18 - 96 months) and the median period to initial ASMs reduction was 0.5 years (range 1-36 months). ASMs reduction was attempted in 17 patients (63%), 5 (29%) of whom had seizure recurrence after initial reduction. Nearly all patient who relapsed regained seizure control after reinstitution of their ASMs regimen. Pre-operative seizure frequency (p=0.002) and occurrence of acute post-operative seizures (p=0.01) were associated with increased risk for seizure recurrence post ASMs reduction. At the end of the observation period, 11% of patients were seizure free without drugs, 52% were seizure free with drugs and 37% still experienced seizures despite ASMs. Compared with pre-operative status, the number of ASMs was reduced in 41% of patients, unchanged in 55% of them and increased in only 4% of them. Successful MRg-LITT for ETLE allows for ASMs reduction in a significant portion of patients and complete ASMs withdrawal in a subset of them. Patients with higher pre-operative seizure frequency or occurrence of acute post operative seizures exhibit higher chances relapse post ASMs reduction.

Stereoelectroencephalography followed by combined electrode removal and MRI-guided laser interstitial thermal therapy or open resection: a single-center series in pediatric patients with medically refractory epilepsy.

Stereoelectroencephalography (SEEG) and MRI-guided laser interstitial thermal therapy (MRgLITT) have emerged as safe, effective, and less invasive alternatives to subdural grid placement and open resection, respectively, for the localization and treatment of medically refractory epilepsy (MRE) in children. Reported pediatric experience combining these complementary techniques is limited, with traditional workflows separating electrode removal and ablation/resection. The authors describe the largest reported series of pediatric epilepsy patients who underwent MRgLITT following SEEG contrasted with a cohort that underwent craniotomy following SEEG, combining ablation/resection with electrode explantation as standard practice. The medical records of all patients with MRE who had undergone SEEG followed by MRgLITT or open resection/disconnection at Boston Children's Hospital between November 2015 and December 2020 were retrospectively reviewed. Primary outcome variables included surgical complication rates, length of hospital stay following treatment, and Engel classification at the last follow-up. Of 74 SEEG patients, 27 (median age 12.1 years, 63% female) underwent MRgLITT and 47 (median age 12.1 years, 49% female) underwent craniotomy. Seventy patients (95%) underwent SEEG followed by combined electrode removal and treatment. Eight MRgLITT cases (30%) and no open cases targeted the insula (p < 0.001). Complication rates did not differ, although trends toward more subdural/epidural hematomas, infarcts, and permanent unanticipated neurological deficits were evident following craniotomy, whereas a trend toward more temporary unanticipated neurological deficits was seen following MRgLITT. The median duration of hospitalization after treatment was 3 and 5 days for MRgLITT and open cases, respectively (p = 0.078). Seizure outcomes were similar between the cohorts, with 74% of MRgLITT and craniotomy patients attaining Engel class I or II outcomes (p = 0.386) at the last follow-up (median 1.1 and 1.9 years, respectively). MRgLITT and open resection following SEEG can both effectively treat MRE in pediatric patients and generally can be performed in a two-surgery workflow during a single hospitalization. In appropriately selected patients, MRgLITT tended to be associated with shorter hospitalizations and fewer complications following treatment and may be best suited for focal deep-seated targets associated with relatively challenging open surgical approaches.

Feasibility of Transcranial Motor Evoked Potentials and Electromyography during MRI-Guided Laser Interstitial Thermal Therapy for Glioblastoma

Intraoperative neuromonitoring (IONM) is routinely used during neurosurgical procedures. Magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy (LITT) is increasingly being used in patients with various brain lesions. Use of IONM (transcranial motor evoked potential [TcMEP] and electromyography [EMG]) during LITT of a brain lesion has not been described previously. In this report, we describe a 70-year-old man who presented with motor weakness in whom imaging revealed a left thalamic lesion. Due to the difficulty in accessing the lesion and proximity to the motor tracts, patient was offered MRI-guided LITT using TcMEP and EMG. The patient underwent satisfactory ablation of the lesion with successful recording of the TcMEP and EMG. Technical nuances related to the set-up and procedure is discussed in this report. No procedure-related complications were encountered. We describe the first report of safety and feasibility of TcMEP and EMG during MRI-guided LITT for left thalamic glioblasatoma. This report paves the way for further prospective investigations regarding the utility of this technique for eloquent brain tumors.

Completion of disconnective surgery for refractory epilepsy in pediatric patients using robot-assisted MRI-guided laser interstitial thermal therapy.

Since 2007, the authors have performed 34 hemispherotomies and 17 posterior quadrant disconnections (temporoparietooccipital [TPO] disconnections) for refractory epilepsy at Sant Joan de Déu Barcelona Children's Hospital. Incomplete disconnection is the main cause of surgical failure in disconnective surgery, and reoperation is the treatment of choice. In this study, 6 patients previously treated with hemispherotomy required reoperation through open surgery. After the authors' initial experience with real-time MRI-guided laser interstitial thermal therapy (MRIgLITT) for hypothalamic hamartomas, they decided to use this technique instead of open surgery to complete disconnective surgeries. The objective was to report the feasibility, safety, and efficacy of MRIgLITT to complete hemispherotomies and TPO disconnections for refractory epilepsy in pediatric patients. Eight procedures were performed on 6 patients with drug-resistant epilepsy. Patient ages ranged between 4 and 18 years (mean 10 ± 4.4 years). The patients had previously undergone hemispherotomy (4 patients) and TPO disconnection (2 patients) at the hospital. The Visualase system assisted by a Neuromate robotic arm was used. The ablation trajectory was planned along the residual connection. The demographic and epilepsy characteristics of the patients, precision of the robot, details of the laser ablation, complications, and results were prospectively collected. Four patients underwent hemispherotomy and 2 underwent TPO disconnection. Two patients, including 1 who underwent hemispherotomy and 1 who underwent TPO disconnection, received a second laser ablation because of persistent seizures and connections after the first treatment. The average precision of the system (target point localization error) was 1.7 ± 1.4 mm. The average power used was 6.58 ± 1.53 J. No complications were noted. Currently, 5 of the 6 patients are seizure free (Engel class I) after a mean follow-up of 20.2 ± 5.6 months. According to this preliminary experience, laser ablation is a safe method for complete disconnective surgeries and allowed epilepsy control in 5 of the 6 patients treated. A larger sample size and longer follow-up periods are necessary to better assess the efficacy of MRIgLITT to complete hemispherotomy and TPO disconnection, but the initial results are encouraging.

The use of stereotactic MRI-guided laser interstitial thermal therapy for the treatment of pediatric cavernous malformations: the SUNYUpstate Golisano Children's Hospital experience.

Cavernous malformations (CM) are central nervous system lesions characterized by interlaced vascular sinusoids coated with endothelial cells without intervening parenchyma. Magnetic resonance imaging-guided laser interstitial thermal therapy (MRIgLITT) is a minimally invasive treatment modality that can precisely treat pathologic cerebral tissue, making it an effective alternative for the management of cavernomas. We describe the outcomes of a series of pediatric patients with cavernous brain malformations treated with MRIgLITT between 2014 and 2018 at our institution. We retrospectively analyzed 11 cavernomas in 6 pediatric patients treated with MRIgLITT. Both the Visualase System® and/or Neuroblate® systems were used. A variation of the surgical technique on the application of the laser was developed. Post-ablation MRIs were obtained to assess ablated areas. A total of 11 cavernomas in 6 patients were treated with MRIgLITT. Median age was 15years (12 to 17years); 75% were males. Presenting symptoms were headache (75%) and seizures (25%). Two patients presented with multiple CMs. All lesions in this study were supratentorial (cerebral hemispheres 81.8%, corpus callosum 9.1%, basal ganglia 9.1%). Our surgical technique was well-tolerated, with no significant adverse events observed. Hospital stay for all patients was less than 48hours. MRIgLITT is an effective minimally invasive technique for the treatment of pediatric CMs. It represents a useful and safe tool, when other therapeutic alternatives may represent a greater risk of surgical morbidity.

SURG-28. ADULT MIDLINE GLIOMAS TREATED WITH LASER INTERSTITIAL THERMAL THERAPY (LITT): OUR COMPARATIVE EXPERIENCE WITH NEEDLE BIOPSY

Abstract INTRODUCTION Adult midline gliomas are rare entities, with a scarcity of available clinical data. These patients have variable courses, with limited evidence to predict outcomes. Emerging evidence suggests that biomolecular profiles may play a significant role in outcomes, so tissue diagnosis is a key component of management. However, the role of cytoreductive therapy, such as Laser Interstitial Thermal Therapy (LITT) remains unknown. To date, only a few studies have described the use of MRI-guided LITT for managing midline gliomas. OBJECTIVE To present a retrospective analysis of a single-center two-surgeon experience treating adult midline gliomas with either biopsy/LITT or biopsy alone. METHODS Patients with midline intraxial tumors surgically treated at our tertiary care referral center were identified using our established database. Twenty-one patients managed either with biopsy/LITT or needle biopsy from 2015 to 2021 were included. Demographics and clinical records including, among others, length of hospital stay, preoperative lesion size, ablation volume, perioperative complications, adjuvant treatment, and stratified overall survival (OS) were collected. RESULTS The two cohorts were composed of 7 patients who underwent LITT, and 14 biopsies. The mean age was 60.95y (25-82). The average tumor volumes were 16.99 cm3 and 15.41 cm3 for LITT and biopsy, respectively. No post-surgical complications were found in the LITT group, one patient had a postsurgical hemorrhage after biopsy. The mean OS was 20.28 ± 9.63 months in the LITT group, which was greater but not statistically significant than in the biopsy group (11.05 ± 4.45 months) (p = 0.605). CONCLUSION Our results show that LITT is as safe as needle biopsy for the treatment of adult midline gliomas, and may offer a survival benefit given its cytoreductive properties.

MRI-guided laser interstitial thermal therapy for deep-seated gliomas in children with neurofibromatosis type 1: report of two cases.

Nearly a quarter of neurofibromatosis type 1 (NF 1)- associated diencephalic low-grade tumors arerefractory to chemotherapy. Addition of alternative treatment options with laser interstitial thermal therapy will havea positive impact on the outcome of these patients. We report on two illustrated cases of pediatric NF1-associated, chemoresistant, WHO grade 1 pilocytic astrocytomas treated with laser interstitial thermal therapy(LITT). Both tumors responded favorably to LITT. LITT should be considered as a treatmentoption for chemoresistant deep-seated NF1-associated low-grade gliomas.

Research progress in the treatment of refractory temporal lobe epilepsy based on stereotactic-electroencephalogram

Temporal lobe epilepsy, with a variety of etiological, symptomatic, electrophysiological characteristics, has the highest incidence among all focal epilepsy, and a high rate of progression to refractory epilepsy. Surgery is an effective treatment, but traditional methods are usually difficult to accurately locate the epileptogenic zone, which may be resolved by stereotactic-electroencephalogram(SEEG) technique. Radiofrequency thermocoagulation and MRI-guided laser interstitial thermal therapy based on SEEG provide a new accurate and minimally invasive choice for refractory epilepsy patients with high surgical risk and difficulty.

A novel technique for frame-based MR-guided laser ablation in an infant.

Hypothalamic hamartomata (HH) not only are usually associated with drug-resistant epilepsy but can also cause precocious puberty and developmental delay. Gelastic seizures are the most common type of seizures. Magnetic resonance image (MRI)-guided laser interstitial thermal therapy (LiTT) is a technique whereby a laser fibre is stereotactically implanted into a target lesion and heat is used to ablate whilst tissue temperature is monitored using MRI thermography. MRI-guided LiTT has proven to be an effective and safe method to treat HH. To use the LiTT system, highly accurate stereotactic fibre implantation is required. This can be achieved by the use of frame-based or frameless neuronavigation techniques. However, these techniques generally involve rigid head immobilisation using cranial pin fixation. Patients need sufficient skull thickness to safely secure the pins and sufficient skull rigidity to prevent deformation. Hence, most of the clinical reports on the use of LiTT for children describe patients aged 2years or older. We report a novel and practical technique of using a paste cast helmet to securely place a stereotactic frame in a 5-month-old infant with HH and drug-resistant epilepsy that allowed the successful application of MRI-guided LiTT.

Voxel-Based Morphometric MRI Postprocessing-Assisted Laser Interstitial Thermal Therapy for Focal Cortical Dysplasia-Suspected Lesions: Technique and Outcomes.

MRI-guided laser interstitial thermal therapy (MRgLITT) is a novel treatment modality for focal cortical dysplasia (FCD). However, identifying the location and extent of subtle FCD by visual analysis during MRgLITT remains challenging. To introduce voxel-based morphometric MRI postprocessing into the procedure of MRgLITT for FCD-suspected lesions and assess the complementary value of the MRI postprocessing technique for the trajectory design and thermal parameter setting of MRgLITT. Junction and normalized fluid-attenuated inversion recovery signal intensity images were used to detect the gray-white matter junction blurring and cortical fluid-attenuated inversion recovery hyperintensity, respectively. According to the 2 postprocessing images, the region of interest (ROI) for ablation was drawn. The main principle of presurgical planning is that the trajectory of the laser fiber was designed as far as possible along the long axis of the ROI while the extent of planned ablation covered the entire ROI. The subsequent intraoperative procedure was performed under the guidance of the presurgical plan. Nine patients with epilepsy with FCD-suspected lesions underwent MRgLITT with the assistance of MRI postprocessing images. Among them, 4 patients were junction positive, 2 patients were normalized fluid-attenuated inversion recovery signal intensity positive, and the remaining 3 patients were positive for both. Postsurgical MRI demonstrated that the ROIs were ablated entirely in 7 patients. Engel Ia, Ib, and IV scores were obtained at 1-year follow-up for 6, 1, and 2 patients, respectively. MRI postprocessing provides complementary information for designing the laser fiber trajectory and subsequent ablation for FCDs.

EPCT-07. Updated report on the pilot study of using MRI-guided laser heat ablation to induce disruption of the peritumoral blood brain barrier to enhance deliver and efficacy of treatment of pediatric brain tumors

Abstract BACKGROUND: MRI-guided laser interstitial thermal therapy (LITT) is a minimally invasive, cytoreductive surgery useful for managing unresectable brain tumors. LITT disrupts the blood brain barrier (BBB) and facilitates chemotherapy delivery. We report the toxicity and outcome for pediatric brain tumors treated on a pilot trial of LITT and chemotherapy. The primary objectives were to quantify peritumoral BBB disruption following LITT and evaluate toxicity and efficacy. METHODS: The trial had two arms, A: patients with newly diagnosed gliomas underwent LITT followed by standard of care management, and B: patients with relapsed malignant brain tumors received 6 weeks of weekly doxorubicin post-LITT followed by maintenance etoposide. RESULTS: Between 2015 – 2018, six patients were enrolled: five on arm A (four with low-grade gliomas, one with high-grade glioma), one on Arm B with progressive anaplastic astrocytoma. All patients tolerated the procedure well; four experienced a transient hemiparesis post-LITT. The Arm B patient progressed and died of disease 2 months and 22 months post-LITT, respectively. The HGG patient received standard therapy and remains without disease progression 44 months post-LITT. One patient with LGG required additional treatment for disease progression 14 months post-LITT. Two patients with LGGs did not require additional therapy, now 51 and 41 months post-LITT. One patient was alive 24 weeks post-LITT and subsequently lost to follow-up. Peritumoral BBB disruption was analyzed in two ways: serum abundance of brain-derived proteins and MRI Dynamic contrast enhancement (DCE). Neuron-specific enolase were measurable in the serum of all patients, using ELISA up to 84 days post-LITT. DCE 2 weeks post-LITT demonstrated increased enhancement and FLAIR signal, consistent with BBB disruption and vasogenic edema. This effect was evident up to 4 months post-procedure. CONCLUSION: LITT is safe in children with brain tumors and can be combined with chemotherapy. DCE and serum brain-derived proteins can measure BBB disruption.

Robot-assisted, real-time, MRI-guided laser interstitial thermal therapy for pediatric patients with hypothalamic hamartoma: surgical technique, pitfalls, and initial results.

Real-time, MRI-guided laser interstitial thermal therapy (MRgLITT) has been reported as a safe and effective technique for the treatment of epileptogenic foci in children and adults. After the recent approval of MRgLITT by the European Medicines Agency in April 2018, the authors began to use it for the treatment of hypothalamic hamartomas (HHs) in pediatric patients with the assistance of a robotic arm. In this study, the authors report their initial experience describing the surgical technique, accuracy of the robotic arm, safety, and efficacy. The laser fiber was placed with the assistance of the stereotactic robotic arm. The accuracy of the robotic arm for this procedure was calculated by comparing the intraoperative MRI to the preoperative plan. Common demographic and seizure characteristics of the patients, laser ablation details, complications, and short-term seizure outcomes were prospectively collected. Sixteen procedures (11 first ablations and 5 reablations) were performed in 11 patients between 15 months and 17 years of age (mean age 6.4 years) with drug-resistant epilepsy related to HHs. The mean target point localization error was 1.69 mm. No laser fiber needed to be repositioned. The mean laser power used per procedure was 4.29 W. The trajectory of the laser fiber was accidentally ablated in 2 patients, provoking transient hemiparesis in one of these patients. One patient experienced postoperative somnolence and syndrome of inappropriate antidiuretic hormone secretion, and 2 patients had transient oculomotor (cranial nerve III) palsy. Fifty-four percent of the patients were seizure free after the first ablation (mean follow-up 22 months, range 15-33 months). All 5 patients who experienced an epilepsy relapse underwent a second treatment, and 4 remain seizure free at least 5 months after reablation. In the authors' experience, the robotic arm was sufficiently accurate for laser fiber insertion, even in very young patients. MRgLITT appears to be an effective treatment for selected cases of HH. MRgLITT for HH is a minimally invasive procedure with appealing safety features, as it allows delivery of energy precisely under real-time MRI control. Nonetheless, complications may occur, especially in voluminous HHs. The amount of delivered energy and the catheter cooling system must be closely monitored during the procedure. A larger sample size and longer follow-up duration are needed to judge the efficacy and safety of MRgLITT for HH more rigorously. This initial experience was very promising.

Acute Postoperative Seizures and Engel Class Outcome at 1 Year Postselective Laser Amygdalohippocampal Ablation for Mesial Temporal Lobe Epilepsy.

MRI-guided laser interstitial thermal therapy (MRgLITT) for mesial temporal lobe epilepsy is a safe, minimally invasive alternative to traditional surgical approaches. Prognostic factors associated with efficacy are debated; preoperative epilepsy duration and semiology seem to be important variables. To determine whether acute postoperative seizure (APOS) after MRgLITT for mesial temporal lobe epilepsy is associated with seizure freedom/Engel class outcome at 1 year. A single-institution retrospective study including adults undergoing first time MRgLITT for mesial temporal lobe epilepsy (2010-2019) with ≥1-year follow-up. Preoperative data included sex, epilepsy duration, number of antiepileptics attempted, weekly seizure frequency, seizure semiology, and radiographically verified anatomic lesion at seizure focus. Postoperative data included clinical detection of APOS within 7 days postoperatively, and immediate amygdala, hippocampal, entorhinal, and parahippocampal residual volumes determined using quantitative imaging postprocessing. Primary outcome was seizure freedom/Engel classification 1 year postoperatively. Of 116 patients, 53% (n = 61) were female, with an average epilepsy duration of 21 (±14) years, average 6 failed antiepileptics (±3), and weekly seizure frequency of 5. APOS was associated with worse Engel class ( P = .010), conferring 6.3 times greater odds of having no improvement vs achieving seizure freedom at 1 year. Residual amygdala, hippocampal, entorhinal, and parahippocampal volumes were not statistically significant prognostic factors. APOS was associated with a lower chance of seizure freedom at 1 year post-MRgLITT for mesial temporal lobe epilepsy. Amygdala, hippocampal, entorhinal, and parahippocampal residual volumes after ablation were not significant prognostic factors.

Withdrawal of Antiepileptic Drugs After MRI–Guided Laser Interstitial Thermal Therapy in Extra-Temporal Lobe Epilepsy (P8-8.005)

Withdrawal of Antiepileptic Drugs After MRI–Guided Laser Interstitial Thermal Therapy in Extra-Temporal Lobe Epilepsy (P8-8.005)

Open surgery or laser interstitial thermal therapy for low-grade epilepsy-associated tumors of the temporal lobe: A single-institution consecutive series

Outcomes of treating low-grade epilepsy-associated tumors (LEATs) in the temporal lobe with MRI-guided laser interstitial thermal therapy (MRgLITT) remain poorly characterized. This study aimed to compare the safety and effectiveness of treating temporal lobe LEATs with MRgLITT versus open resection in a consecutive single-institution series. We reviewed all adult patients with epilepsy that underwent surgery for temporal lobe LEATs at our institution between 2002 and 2019, during which time we switched from open surgery to MRgLITT. Surgical outcome was categorized by Engel classification at >12mo follow-up and Kaplan–Meir analysis of seizure freedom. We recorded hospital length of stay, adverse events, and available neuropsychological results. Of 14 total patients, 7 underwent 9 open resections, 6 patients underwent MRgLITT alone, and 1 patient underwent an open resection followed by MRgLITT. Baseline group demographics differed and were notable for preoperative duration of epilepsy of 9.0 years (range 1–36) for open resection versus 14.0 years (range 2–34) for MRgLITT. Median length of stay was one day shorter for MRgLITT compared to open resection (p=<.0001). There were no major adverse events in the series, but there were fewer minor adverse events following MRgLITT. At 12mo follow-up, 50% (5/10) of patients undergoing open resection and 57% (4/7) of patients undergoing MRgLITT were free of disabling seizures (Engel I). When comparing patients who underwent similar procedures in the dominant temporal lobe, patients undergoing MRgLITT had fewer and milder material-specific neuropsychological declines than patients undergoing open resections. In this small series, MRgLITT was comparably safe and effective relative to open resection of temporal lobe LEATs.